Electronic assembly for an inverter

ABSTRACT

An electronic assembly for an inverter comprises a substrate having a dielectric layer and metallic circuit traces. A plurality of terminals are arranged for connection to a direct current source. A first semiconductor and a second semiconductor are coupled together between the terminals of the direct current source. A primary metallic island (e.g., strip) is located in a primary zone between the first semiconductor and the second semiconductor. The primary metallic island has a greater height or thickness than the metallic circuit traces. The primary metallic island provides a heat sink to radiate heat.

RELATED APPLICATION

This document (including the drawings) claims priority and the benefitof the filing date based on U.S. provisional application No. 61/971,590,filed Mar. 28, 2014 under 35 U.S.C. §119 (e), where the provisionalapplication is hereby incorporated by reference herein.

FIELD OF THE INVENTION

This disclosure relates to an electronic assembly for an inverter.

BACKGROUND

In certain prior art, an electronic assembly may have inadequate heatdissipation that reduces the longevity or maximum power output of powersemiconductor switches. Accordingly, there is need for an electronicassembly for an inverter with improved heat dissipation.

SUMMARY

In one embodiment, an electronic assembly for an inverter comprises asubstrate having a dielectric layer and metallic circuit traces. Aplurality of terminals is arranged for connection to a direct currentsource. A first semiconductor and a second semiconductor are coupledtogether between the terminals of the direct current source. A primarymetallic island (e.g., strip) is located in a primary zone between thefirst semiconductor and the second semiconductor. The primary metallicisland has a greater height or thickness than the metallic circuittraces. The primary metallic island provides a heat sink to radiateheat.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of the electronicassembly for an inverter.

FIG. 2 is a perspective, exploded view of the electronic assembly ofFIG. 1 that further illustrates an upper housing assembly and a lowerhousing assembly.

FIG. 3 is a perspective view of the electronic assembly of FIG. 2 thatis assembled.

FIG. 4 is a first cross section of FIG. 3 along reference line 4-4 ofFIG. 3, where reference line 4-4 is also shown in FIG. 1 and FIG. 2.

FIG. 5 is a second cross section of FIG. 3 along reference line 5-5 ofFIG. 3, where reference line 5-5 is also shown in FIG. 1 and FIG. 2.

FIG. 6 is a third cross section of FIG. 3 along reference line 6-6 ofFIG. 3, where reference line 6-6 is also shown in FIG. 1 and FIG. 2.

FIG. 7 is a cross section of one embodiment of an electronic assemblythat illustrates an enlarged portion of rectangular region 7 of FIG. 4.

FIG. 8 is a cross section of another embodiment that is analogous to thesmall enlarged portion of rectangular region 7 of FIG. 4, where athermal interface material is present.

FIG. 9 is a cross section of yet another embodiment that is analogous tothe small enlarged portion of rectangular region 7 of FIG. 5, where aconductive via and a ground plane is present.

FIG. 10 is an illustrative example of a fluid cooling system thatincorporates the electronic assembly of FIG. 1.

Like reference numbers in different drawings indicate like elements.

DETAILED DESCRIPTION

In one embodiment, FIG. 1 shows a circuit board assembly 11 of anelectronic assembly 200 for an inverter. The circuit board assembly 11,of the electronic assembly 200, comprises a substrate 34 having adielectric layer 54 and one or more metallic circuit traces on one orboth sides of the substrate 34. Direct current terminals are arrangedfor connection to a direct current source. A first semiconductor 20 anda second semiconductor 22 are coupled together between the terminals ofthe direct current source. A primary metallic island 24 (e.g., strip) islocated in a primary zone between the first semiconductor 20 and thesecond semiconductor 22. The primary metallic island 24 has a greaterheight or thickness than the metallic circuit traces. The primarymetallic island 24 provides a heat sink to radiate heat.

In one embodiment, the direct current terminals (42, 44) comprisesurface mount connectors, such as a female surface mount connector thatis generally cylindrical and that comprises a metal or an alloymaterial. Each connector (36, 38, 40, 42, 44) may comprise a surfacemount connector. Each connector (36, 38, 40, 42, 44) may have a mountingpad 48 at one end for mounting to a corresponding conductive pad 50 onthe substrate 34, where the conductive pad 50 is associated with orelectrically connected to one or more conductive traces (e.g., 406).

As illustrated, the electronic assembly 200 shows three phases or threeswitching sections, where each phase has a first semiconductor 20coupled to a second semiconductor 22. At the inputs of each switchingsection, the first direct current terminal 42 and the second directcurrent terminal 44 provide direct current to each phase or switchingsection. The output of each switching section is defined by set ofalternating current connectors.

For each phase, the first semiconductor 20 may comprise a semiconductorswitch (e.g., low-side semiconductor switch) that with at least one ofits switching terminals coupled to one side (e.g., low side or negativeterminal) of the direct current bus or direct current source that feedsthe direct current terminals. For example, the switching terminals mayrefer to the emitter and collector if the first semiconductor 20comprises a transistor, or the switching terminals may refer to thesource and drain if the first semiconductor 20 comprises a field effecttransistor. A control terminal (e.g., base or gate) of the firstswitching transistor is coupled to a control circuit or a driver that isnot shown.

For each phase, the second semiconductor 22 may comprise a semiconductorswitch (e.g., high-side semiconductor switch) that with at least one ofits switching terminals coupled to one side (e.g., high side or positiveterminal) of the direct current bus or direct current source that feedsthe direct current terminals. For example, the switching terminals mayrefer to the emitter and collector if the first semiconductor 20comprises a transistor, or the switching terminals may refer to thesource and drain if the first semiconductor 20 comprises a field effecttransistor. A control terminal (e.g., base or gate) of the firstswitching transistor is coupled to a control circuit or a driver that isnot shown.

The output of each switching section is defined by set of alternatingcurrent (AC) connectors (36, 38, 40). As illustrated in FIG. 1, thealternating current connectors comprise a first AC connector 36, asecond AC connector 38 and a third AC connector 40 for the first phaseswitching section, the second phase switching section and third phaseswitching section, respectively. In one embodiment, the AC connectors(36, 38, 40) comprise surface mount connectors, such as a female surfacemount connector that is generally cylindrical and that comprises a metalor an alloy material. Each surface mount connector (36, 38, 40) may havea mounting pad 48 at one end for mounting to a corresponding conductivepad 50 on the substrate 34, where the conductive pad 50 is associatedwith or electrically connected to one or more conductive traces (e.g.,406).

For each phase, primary metallic island 24 (e.g., strip) is located in aprimary zone between the first semiconductor 20 and the secondsemiconductor 22. In one configuration, each primary metallic island 24generally has a greater height or thickness than the metallic circuittraces. For example, the primary metallic island 24 provides a heat sinkto radiate or conduct heat to an interior of the first enclosure portion100 or the first housing assembly 132. The first enclosure portion 100may communicate the radiated or conducted heat toward a conduit ortransition for circulating or conveying coolant through the firstenclosure portion 100. In one embodiment, the primary metallic island 24comprises a copper pour.

A secondary metallic island 26 (e.g., strip) is located in a secondaryzone between adjacent surface mount connectors or between any DCterminal (42, 44) and any adjacent AC connector (36, 38, 40). Forexample, the secondary metallic island 26 provides a heat sink toradiate/conduct heat to an interior of the first enclosure portion 100or the first housing assembly 132. The first enclosure portion 100 maycommunicate the radiated or conducted heat towards a conduit ortransition for circulating or conveying coolant through the firstenclosure portion 100. In one embodiment, the secondary metallic island26 comprises a copper pour.

A tertiary metallic island 28 is located on the substrate 34 between asecond semiconductor switch 22 and a corresponding AC connector, or moregenerally between a second semiconductor switch 22 and surface mountconnector. In one configuration, each tertiary metallic island 28generally has a greater height or thickness than the metallic circuittraces. For example, the tertiary metallic island 28 provides a heatsink to radiate or conduct heat to an interior of the first enclosureportion 100 or the first housing assembly 132. The first enclosureportion 100 may communicate the radiated or conducted heat toward aconduit or transition for circulating or conveying coolant through thefirst enclosure portion 100. In one embodiment, the tertiary metallicisland 28 comprises a copper pour.

A quaternary metallic island 30 is located on the substrate 34 proximateto a first semiconductor 20 switch (e.g., for each phase). In oneconfiguration, each quaternary metallic island 30 generally has agreater height or thickness than the metallic circuit traces. Forexample, the quaternary metallic island 30 provides a heat sink toradiate or conduct heat to an interior of the first enclosure portion100 or the first housing assembly 132. The first enclosure portion 100may communicate the radiated or conducted heat toward a conduit ortransition for circulating or conveying coolant through the firstenclosure portion 100. In one embodiment, the quaternary metallic island30 comprises a copper pour.

In one embodiment, the first semiconductor switch 20 and the secondsemiconductor switch 22 comprise metal-oxide semiconductor field-effecttransistors (MOSFET's), or insulated gate bi-polar transistors (IGBT's)composed of silicon, silicon carbide, gallium nitride, or othersemiconductor material that is packaged in the form of planar chipsets.These chipsets could be realized in planar shape, packaged and ready forpick-and-placement manufacturing processes on substrate. The thermalmanagement is enhanced by a housing (with integral coolant channelswithin the first enclosure portion 100 (in FIG. 4) and the secondenclosure portion 102) offers the opportunity to raise current density(A/cm2) of the substantially planar first semiconductor switch 20 andthe second semiconductor switch 22 (e.g., MOSFET/IGBT chipsets).Therefore, at a given current rating of electronics assembly 200 it ispossible to use a die of smaller size than otherwise possible for thesemiconductor material used in the first semiconductor switch 20 and thesecond semiconductor switch 22, depending of type of switching devicesused in inverter design.

The reduction of the die size of the semiconductor or package size ofthe first semiconductor switch 20 and the second semiconductor switch 22is supported by double-sided thermal management of the substantiallyplanar chipsets coupled with lateral withdrawal of heat flux throughpower interconnects. Accordingly, the first semiconductor switch 20 andthe second semiconductor switch 22 are placed in a thermally managedenvironment that allows each semiconductor die to operate at lowerjunction temperature (Tj). Here, the thermally managed environment maybe referred to as multi-sided thermal management of power switchingdevices (20, 22). A lower value of Tj at a given power offersopportunity to decrease the die size and package size the firstsemiconductor switch 20 and the second semiconductor switch 22 withoutcompromising or decreasing inverter capability. Decreasing the size ofthe die of Si, SiC and GaN material in the semiconductor switches (20,22) could proportionally increase the area of the conductive traces,islands, heat sink areas, or bus bar around each chipset making it moreeffective for lateral flow of heat flux from die to the coolant channelin within the first enclosure portion 100 (FIG. 4) and the secondenclosure portion 102.

In one configuration, a group of capacitors 56 may be mounted on or tothe substrate 34. For example, as shown in FIG. 1, a first array ofcapacitors 56 is mounted on a first side of the substrate 34, whereas asecond array of capacitors 56 is mounted on a second side of substrate34 opposite the first side. Although two rows of four capacitors 56 areshown on each side of the substrate 34, any suitable number ofcapacitors 56 may be used. As shown, each capacitor 56 has a firstterminal 58 and a second terminal 60. In one configuration, eachcapacitor 56 may comprise an electrolytic capacitor 56.

In one embodiment, the capacitors comprise surface-mount, low-profilefilm capacitors. The package of the capacitors 56 with high-surface areaconductive terminals (58, 60) and thermal interface material around thecapacitors 56 facilitates conductive thermal management for lowertemperature rise per ampere current filtered and higher ampere per unitcapacitance (e.g., micro-Farad (uF)) required or used. The thermalinterface material comprises a cured (e.g., substantially cross-linked)polymer, elastomer or plastic or solid dielectric material that ispositioned, inserted, injected as a resin in an uncured state, in liquidphase, or in a semi-solid phase between the interior of the firstenclosure and the second enclosure and the capacitors 56 for enhancedheat dissipation. The capacitors 56 can be configured as parts that canwithstand lead-free reflow temperature profile needed for surface mountmanufacturing line, for example.

As illustrated in FIG. 1, an ancillary substrate 46 is mounted in adifferent plane that is generally parallel to or offset from the planeof the substrate 34. A connector has a dielectric portion and terminals,where the connector is mounted on or through the ancillary substrate 46.The ancillary circuit board may have one or more openings 52. Forexample, the ancillary circuit board may have ancillary openings 52 foreach phase or switching section, such that a second enclosure portion102 or a second housing assembly 134 may contact or be in closeproximity to the switching section to conduct heat away from theswitching section.

In an alternate embodiment, the heat is conducted away from one or moremetallic islands (e.g., 24, 28, 30) through one or more thermallyconductive vias 900 (e.g., thermally conductive through-holes, thermallyconductive blind vias, or thermally and electrically conductive vias, orother structures) connected between the one or more metallic islands(e.g., 24, 28, 30) and a heat-sink island 901 or heat sink on anopposite side of the substrate 34, as best illustrated in FIG. 9. In oneembodiment, the heat sink or heat-sink island 901 is isolated on aphase-by-phase basis, such that each phase heat-sink island (e.g., firstphase heat sink island) is mechanically separate and electricallyisolated (e.g., electromagnetically isolated over an operationalfrequency range) from respective other phase heat sink islands (e.g., onan underside or the opposite side of the substrate 34) of the otherphase outputs (e.g., second phase heat-sink island and third phaseheat-sink island) of the electronic assembly 200. Further, cumulativewith or separate from the heat transfer through the thermally conductivevias 900, the heat is transferred to the fluid or coolant in the coolantchannel (e.g., within the first enclosure portion 100 or secondenclosure portion).

The circuit board assembly 11 of electronic assembly 200 may comprise aplurality of first surface mount connectors mounted on the substrate 34that are electrically connected to the terminals and a secondarymetallic island 26 located in a secondary zone between adjacent surfacemount connectors.

FIG. 2 illustrates a housing assembly that encloses the circuit boardassembly 11 of FIG. 1. In one embodiment, the housing comprises a firsthousing assembly 132 and a second housing assembly 134, where the firsthousing assembly 132 mates with the second housing assembly 134. Thefirst housing assembly 132 comprises a first enclosure portion 100 and athird enclosure portion 104. The second housing assembly 134 comprises asecond enclosure portion 102 and a fourth enclosure portion 106.

As shown, the first enclosure portion 100 and the second enclosureportion 102 have mounting holes (108, 110) for receiving one or morefasteners 117 to fasten or joint the first enclosure portion 100 to thesecond enclosure portion 102, where the circuit board assembly 11 ofFIG. 1 is sandwiched between the first and second enclosure portions 102or enclosed by the first and second enclosure portions 102. The thirdenclosure portion 104 is secured to or attached to the first enclosureportion 100. For example, the third enclosure portion 104 may comprise aheat sink or upper cover of the housing assembly. Similarly, the fourthenclosure portion 106 may comprise a heat sink or a lower cover of thehousing assembly. The fourth enclosure portion 106 is secured to orattached to the second enclosure portion 102. In one embodiment, thefirst enclosure portion 100 and the second enclosure portion 102 arecomposed of a polymer, a plastic, a polymer matrix with a filler, suchas reinforced fiber or carbon fiber. For instance, the first enclosureportion 100 and the second enclosure portion 102 may be manufactured bya three-dimensional printer capable of printing a three-dimensionalstructure with various openings 52, conduits or passageways forconducting fluid to cool the circuit board assembly 11 or its heatgenerating components. In an illustrative configuration, the thirdenclosure portion 104 and the fourth enclosure portion 106 may beconstructed of a metal material, a metallic material, an alloy materialor heat sink material, such as aluminum, cast aluminum. The thirdenclosure portion 104 and the fourth enclosure portion 106 may beconstructed with a three-dimensional printer capable of printing athree-dimensional structure from a polymer, plastic or resin thatcontains electrically conductive particles, such as metallic particlesto promote heat dissipation, or any suitable thermally conductivepolymeric materials.

A first interior surface of the first enclosure portion 100 may conformsubstantially in size and shape to mate or interlock with the one sideof the circuit board assembly 11, whereas a second interior surface ofsecond enclosure portion 102 may conform substantially in size and shapeto mate or interlock with an opposite side. For example, the firstenclosure portion 100 has generally cylindrical recesses that engagewith corresponding AC connectors and DC terminals on the substrate 34.Further, the first enclosure portion 100 has a first switching section75 recess that is generally rectangular, polyhedron-like, or thatotherwise conforms to the shape and size of the first switching section75 above the substrate 34; a second switching section 77 recess 126 thatis generally rectangular, polyhedron-like, or that otherwise conforms tothe shape and size of the second switching section 77 above thesubstrate 34; a third switching section 79 recess that is generallyrectangular, polyhedron-like, or that otherwise conforms to the shapeand size of the third switching section 79 above the substrate 34. Withrespect the capacitor 56 arrays, the first enclosure has an aggregatecapacitor recess or individual capacitor recesses that conform to thesize and shape of corresponding capacitors 56 on the circuit boardassembly 11.

The second enclosure portion 102 has raised protrusions 124 that foreach switching section, where the raised protrusions 124 can contact theunderside of each switching section. In an alternate embodiment, thesecond enclosure portion 102 has raised protrusions that for eachswitching section, where the raised protrusions can contact theunderside of each switching section with a thermally conductiveinterface material, as illustrated in FIG. 8. The thermally conductiveinterface material comprises an intervening thermally conductiveadhesive, an intervening thermally conductive grease, or an interveningthermally conductive polymer. As shown, the second enclosure portion 102has an aggregate capacitor 56 recess that conforms to the size and shapeof corresponding capacitors 56 on the circuit board assembly 11.

As shown, the first enclosure portion 100 has a first inlet 116 and afirst outlet 118 for receiving and exhausting a coolant, respectively.Similarly, the second enclosure portion 102 has a second inlet 120 and asecond outlet 122 for receiving and exhausting a coolant, respectively.FIG. 10 provides an illustrative example of one embodiment of how thecoolant is circulated or conveyed through the electronic assembly 200 toprovide enhanced cooling of the switching sections, capacitors 56 orother components within the electronic assembly 200.

FIG. 3 shows the electronic assembly 200 of FIG. 2 in its assembledstate. Each of the AC connectors (36, 38, 40) and DC connectors (42, 44)may be connected to conductors 130 or cables via mating connectors 128(e.g., male plugs) that mate with the corresponding connectors (e.g.,surface mount connectors or female connectors) of the electronicassembly 200. For example, the DC connectors (42, 44) may be connectedor coupled to a direct current (DC) source, such as a battery, agenerator, a fuel cell electrical output, or rectified alternator.Meanwhile, the AC connectors may be coupled or connected tocorresponding phases of an electric motor (e.g., any conventional,unconventional or mutually coupled switched reluctance motor orpermanent magnet alternating current motor) to be controlled, or analternator or other electric machine.

FIG. 4 illustrates a cross section of the electronic assembly 200 alongreference line 4-4. Like reference numbers in FIG. 1 through FIG. 4,inclusive, indicate like elements or features. The cross section of FIG.4 shows the coolant channels (420, 422, 424, 421, 428) that extendbetween the first inlet 116 and the first outlet 118 of the firsthousing assembly 132 or the first enclosure portion 100. The crosssection of FIG. 4 also shows the coolant channels (411, 412, 414, 416,418) that extend between the second inlet 120 and the second outlet 122of the second housing assembly 134 or the second enclosure portion 102.In one embodiment, between the first inlet 116 and the first outlet 118,a first coolant channel (420, 422, 424, 421, 428) is fully containedwithin the first enclosure portion, which eliminates the need forcooperating ports in the electronic assembly 200 for the transfer ofcoolant between the first enclosure portion 100 and the second enclosureportion 102. Similarly, between the second inlet 120 and the secondoutlet 122, a second coolant channel is fully contained within thesecond enclosure portion 102, which eliminates the need for anycooperating ports in the electronic assembly 200 for the transfer ofcoolant between the first enclosure portion 100 and the second enclosureportion 102. Accordingly, any gaskets, seals, or adhesive between thosecooperating ports, in the first enclosure portion 100 and the secondenclosure portion 102, are eliminated and do not leak.

For illustrative purposes, FIG. 4 will be described such that thevisible portion of the first coolant channel is designated as anoutbound portion (420, 422, 424, 421, 428) of the first coolant channel,although the first coolant channel has an inbound portion that lookssimilar to the outbound portion. The outbound portion and the inboundportion of the first coolant channel are generally interchangeablebecause they are merely defined with respect to the direction of fluidor coolant flow, and with respect to the orientation of the pumpdischarge or pump input with respect the first inlet and first outlet.For example, the inbound portion and the outbound portion are redefinedwhen the connections between the first inlet, the first output to thepump are reversed.

In one embodiment, an outbound portion (420, 422, 424, 421, 428) of thefirst coolant channel comprises a first inlet transverse chamber 420, aset of first inner outbound conduits 422, a set of first outboundtransitions 424, a set of first outer outbound conduits 421, and a firstouter transverse chamber 428, a set first inbound outer conduits, a setof first inbound transitions, a set of first inner inbound conduits. Theoutbound portion (420, 422, 424, 421, 428) of first coolant channel iscoupled between the first inlet 116 and the first outlet 118 and mayfollow a circuitous path or serpentine path through the first enclosureportion 100 between the first inlet 116 and the first outlet 118. Theoutbound portion (420, 422, 424, 421, 428) of the first coolant channelcan be described in conjunction with the direction of fluid flow fromthe first inlet 116 to the first outlet 118, where the outbound pathtravels from the first inlet 116 and where the inbound path travelstoward the first outlet 118.

In the first coolant channel, the first inlet 116 communicates with thefirst inlet transverse chamber 420. A set of first inner outboundconduits 422 comprise one or more first inner outbound conduitsemanating from (e.g., longitudinally in FIG. 4 in the plane of thesheet) the first inlet transverse chamber 420. The respective set ofinner outbound conduits 422 is coupled to a corresponding set of firstoutbound transitions 424. In one embodiment, each first outboundtransition 424 region may comprise a substantially spiral, substantiallyelliptical, or substantially circular, or otherwise curved channel thatlinks or connects a respective one of the first inner outbound conduits422 to corresponding one of the first outer outbound conduits 424. Inone configuration, one end of the set of first outer outbound conduits421 is coupled to a corresponding set of the first outbound transitions424, whereas the opposite end of the set of first outer outboundconduits 421 is coupled to the first outer transverse chamber 428.

In the second coolant channel (411, 412, 414, 416, 418), the secondinlet 120 communicates with the second inlet transverse chamber 411. Aset of second inner outbound conduits 412 comprise one or more secondinner outbound conduits emanating from (e.g., longitudinally in FIG. 4in the plane of the sheet) the second inlet transverse chamber 411. Therespective set of inner outbound conduits 412 is coupled to acorresponding set of second outbound transitions 414. In one embodiment,each second outbound transition 414 may comprise a substantially spiral,substantially elliptical, or substantially circular, or otherwise curvedchannel that links or connects a respective one of the second inneroutbound conduits 412 to corresponding one of the second outer outboundconduits 416. In one configuration, one end of the set of second outeroutbound conduits 416 is coupled to a corresponding set of the secondoutbound transition 414, whereas the opposite end of the set of secondouter outbound conduits 416 is coupled to the second outer transversechamber 418, or a series of generally parallel curved conduits or loops.

In one embodiment, one or more of the transitions (424, 414) maycomprise a substantially spiral, substantially elliptical, substantiallycircular or otherwise curved channel that circumnavigates or surroundsan exterior of a connector (e.g., surface-mount connector) associatedwith the substrate 34. Accordingly, each such transition (e.g., 424) hasan inner diameter or generally cylindrical surface 410 that isconfigured to mate with, nest with, or interlock with a generallycylindrical outer surface 408 of the connector 40. As shown in FIG. 4, atransition 424 (e.g., first transition or upper transition) surroundsthe exterior of the connector 40 in close proximity for heat transfer ofthermal energy from the connector 40 to the coolant in the first coolantchannel, whereas the transition 414 (e.g., second transition or lowertransition) does not surround the connector (e.g., 40) in theconfiguration shown. The transition 414 may be composed of or associatedwith a metal or metallic structure in close proximity to a heat sink orfourth enclosure portion 106.

In one illustrative configuration, first enclosure portion 100 has aninner surface with a mating shape and size that corresponds to thecontour or adjoining first surface mount connectors (36, 38, 40) or thatcorresponds to direct terminals (42, 44). The first enclosure portion100 has a transition region (e.g., 414) of channels in a spiral patharound an outer diameter of the first surface mount connector to providethermal path for heat dissipation from the surface mount connector (36,38, 40) or direct terminals (42, 44). For example, the inner surface issubstantially cylindrical and engages a corresponding outer cylindricalsurface of a corresponding one of the first surface mount connectors(36, 38, 40) or direct terminals (42, 44).

The first housing assembly 132 comprises a first enclosure portion 100that overlies the substrate 34 and the primary metallic island 24;wherein the heat is conducted away from the primary metallic island 24through a first enclosure portion 100 in contact with, above or in closeproximity to the primary metallic island 24. For example, the heat isconducted from the primary metallic island 24 through the enclosureportion to the ambient air around the first enclosure portion 100.Cumulative with or separate from the heat transfer to the ambient airaround the first enclosure portion 100, the heat is transferred to thefluid or coolant in the coolant channel. Heat or thermal energy isconducted away from the tertiary metallic island 28 through a firstenclosure portion 100 in contact with, above or in close proximity tothe tertiary metallic island 28. Heat or thermal energy is conductedaway from a quaternary metallic island 30 through a first enclosureportion 100 in contact with, above or in close proximity to thequaternary metallic island 30. As illustrated, one or more conductivetraces are on one or more sides of the substrate 34. The connector 32may be surface-mounted to conductive pads on one side of the substrate,and may be mounted through a connector opening 15 (in FIG. 2) in thefirst enclosure portion 100.

In FIG. 4, the third enclosure portion 104 has one or more fins 402 orradiating elements for radiating thermal energy. In an alternativeembodiment, the third enclosure portion 104 may be configured as a heatsink and forged, cast, stamped or otherwise formed from metal, an alloyor metallic material. Similarly, the fourth enclosure portion 106 hasone or more fins 404 or radiating elements for radiating thermal energy.In an alternative embodiment, the fourth enclosure portion 106 may beconfigured as a heat sink and forged, cast, stamped or otherwise formedfrom metal, an alloy or metallic material.

FIG. 5 shows a cross section of the electronic assembly 200 alongreference line 5-5. Like reference numbers in FIG. 4 and FIG. 5 indicatelike elements. The cross section of FIG. 5 does not show the crosssection of any transitions or the cross section any AC connector (36,38, 40) or DC terminal (42, 44). Further, the cross section of FIG. 5falls between the first coolant channel and the second coolant channelwithin the first enclosure portion 100 and the second enclosure portion102, respectively.

FIG. 6 shows a cross section of the electronic assembly 200 alongreference line 6-6. Like reference numbers in FIG. 4 and FIG. 6 indicatelike reference numbers. The cross section of FIG. 4 may disclose anoutbound transition and corresponding outbound portions of the first andsecond conduits, whereas the cross section of FIG. 5 may show an inboundtransition and the corresponding inbound portions of the first andsecond conduits.

A set of first outer inbound conduits 521 comprise one or more firstouter inbound conduits 521 emanating from (e.g., longitudinally in FIG.4 in the plane of the sheet) the first outer transverse chamber 528, ora series of generally parallel curved conduits or loops. The respectiveset of outer inbound conduits 521 is coupled to a corresponding set offirst inbound transitions 524. In one embodiment, each first inboundtransition 524 may comprise a substantially spiral, substantiallyelliptical, or substantially circular, or otherwise curved channel thatlinks or connects a respective one of the first outer inbound conduits521 to corresponding one of the first inner inbound conduits 522. In oneconfiguration, one end of the set of first inner inbound conduits 522 iscoupled to a corresponding set of the first inbound transitions 524,whereas the opposite end of the set of first inner inbound conduits 522is coupled to the first inlet transverse chamber 520. The first inlettransverse chamber may be coupled to the first inlet 116 or the firstoutlet 118.

A set of second outer inbound conduits 516 comprise one or more secondouter inbound conduits 516 emanating from (e.g., longitudinally in FIG.4 in the plane of the sheet) the second outer transverse chamber 518 ora series of generally parallel curved conduits or loops. The respectiveset of second outer inbound conduits 516 is coupled to a correspondingset of second inbound transitions 514. In one embodiment, each secondinbound transition 514 may comprise a substantially spiral,substantially elliptical, or substantially circular, or otherwise curvedchannel that links or connects a respective one of the second outerinbound conduits 516 to corresponding one of the second inner inboundconduits 512. In one configuration, one end of the set of second innerinbound conduits 512 is coupled to a corresponding set of the secondinbound transitions 514, whereas the opposite end of the set of secondinner inbound conduits 512 is coupled to the second outlet transversechamber 511. The second outlet transverse chamber 511 may be coupled tothe second inlet 120 or the second outlet 122.

In FIG. 4 through FIG. 6, the first enclosure portion 100 comprises agroup of channels or micro-channels within the first enclosure portion100 for conveying fluid or coolant, and where an inner surface of thefirst enclosure portion 100 is in contact with, above or in closeproximity to one or more metallic islands (e.g., the primary metallicisland 24, secondary metallic island 26, tertiary metallic island 28, orquaternary metallic island 30) for transfer of the heat from themetallic islands to the coolant or fluid within the channel ormicro-channels. In one configuration, each AC connector (36, 38, 40)comprises surface mount connector is mounted on the substrate 34. EachAC connector is electrically connected to each corresponding phaseoutput terminal of a switching section, such as the first semiconductor20 and the second semiconductor 22. A tertiary metallic island 28 islocated in a tertiary zone between adjacent connectors (26, 38, 40, 42,44) or between adjacent surface mount connectors.

In one example, the second enclosure portion 102 comprises a group ofchannels or micro-channels within the second enclosure portion 102, andwhere an inner surface of the second enclosure portion 102 is in contactwith, above or in close proximity an opposite side of the substrate 34on which one or more metallic islands are found for transfer of the heatfrom one or more metallic islands. In one configuration, the firstsemiconductor 20 and the second semiconductor 22 comprise surface mounttransistors that are mounted on the substrate 34 and electricallyconnected to corresponding ones of the metallic circuit traces (e.g.,406 in FIG. 4) and wherein the second enclosure portion 102 has an innersurface with a mating shape and size that corresponds to the contour oradjoining surface of the opposite side of the substrate 34 and anyassociated components (e.g., electrical or electronic components) on thesubstrate 34.

FIG. 7 illustrates an enlarged rectangular portion of the cross sectionof the electronic assembly 200 shown in FIG. 4. FIG. 7 clearly shows thetransition that engages a connector (e.g., surface mount connector) thatis connected to corresponding connector portion (e.g., plug) andconductor. Here, the corresponding connector portion is illustrated asright-angle connector although any connector (e.g., straight connectoror ordinary connector) may fall within the scope of the disclosure.

In FIG. 7, the first enclosure portion 100 comprises a first conduit. Inturn, the first conduit comprises a group of generally parallel andlongitudinally extending channels or first micro-channels within thefirst enclosure portion 100, where an adjoining portion of the firstenclosure portion 100 provides a thermal path between one or moremetallic islands and the first conduit. As indicated previously, themetallic islands include one or more of the following islands: a primarymetallic island 24, a secondary metallic island 26, a tertiary metallicisland 28 and a quaternary metallic island. In one embodiment, thechannels are synonymous with the inbound and outbound paths previouslydescribed herein.

As illustrated in FIG. 7, the second enclosure portion 102 comprises asecond conduit. In turn, the second conduit comprises a group ofgenerally parallel and longitudinally extending channels or secondmicro-channels within the second enclosure portion 102, where anadjoining portion of the second enclosure portion 102 provides a thermalpath between one or more metallic islands and the second conduit. Asindicated previously, the metallic islands include one or more of thefollowing islands: a primary metallic island 24, a secondary metallicisland 26, a tertiary metallic island 28 and a quaternary metallicisland 30.

The third enclosure portion 104 is secured to the first connectorportion. The third connector portion comprises a cover or heat sink(e.g., cover with external cooling fins or generally parallel ridges),to provide a supplemental path for transfer of the heat from one or moremetallic islands of the electronic assembly 200. The fourth enclosureportion 106 is secured to the second connector portion. The fourthconnector portion comprises a cover or heat sink (e.g., cover withexternal cooling fins or generally parallel ridges), to provide asupplemental path for transfer of the heat from one or more metallicislands of the electronic assembly 200.

The electronic assembly 200 of FIG. 8 is similar to the electronicassembly 200 of FIG. 7, except that the electronic assembly 200 of FIG.8 further includes a thermal interface material (801, 802, 803), athermally conductive adhesive or thermally conductive lubricant. Forexample, the thermal interface material (801, 802, 803) is used betweenthe primary metallic island 24 and the first enclosure portion 100,between the tertiary metallic island 28 the first enclosure portion 100,and between the quaternary metallic island 30 and the first enclosureportion 100. Like reference numbers in FIG. 7 and FIG. 8 indicate likeelements or features.

In one embodiment, the thermal interface material is a gap filer thatcan be used between the circuit board assembly 100 and an interior ofthe electronic assembly 200. For example, a thermal interface materialmay be injected, forced or put into a first gap between the circuitboard assembly 100 and the generally conforming interior surface of thefirst enclosure portion 100 and between a second gap between the circuitboard assembly 100 and the second enclosure portion 102. The thermalinterface material can fill irregular depressions, recesses or voids ina layer. The thermal interface material is well suited for leavingbehind zero or negligible bond lines after the thermal interfacematerial is cured. Thermal interface material is used to avoid shortcircuits and metal-to-metal contact, where a live metal terminal (or anelectrically conductive structure at a potential different than ground)may contact a metal component at electrical ground potential. Thethermal interface material is well suited for carrying heat away fromactive components to coolant channels formed in the first enclosureportion 100, the second enclosure portion 102, or in the housing. Forexample, the thermal interface material can be in direct connect withthe metallic islands (e.g., 30, 24, 28) or heat sinking strips on thesubstrate. Further, the thermal interface material may overlie thecapacitors 56 and may fill a void between the capacitors 56 and theinterior of the first enclosure portion 100 and the second enclosureportion 102 to draw or conduct heat away from the capacitors 52.

In one configuration, the thermal management material is applied (e.g.,sprayed on) and when it cures it is a dielectric structure withrelatively high thermal conductivity, such as about 240Watt/meter-Kelvin in the x-y direction and about 5 Watt/meter-Kelvin inthe Z direction. Where the x-y plane is the plane of the surface of thesubstrate 34 such that heat transfer theoretically takes place with ananisotropic gradient within the electronic assembly 200.

As illustrated in FIG. 1, where flip chip or flip die methods are usedfor the first semiconductor switch 20 and the second semiconductorswitch 22, a first thermal interface material layer could overlie (or bebonded to) one side of the substrate 34 and second thermal interfacematerial layer could overlie (or be bonded to) the first thermalinterface material layer, where the multiple thermal interface layerstend to provide shock absorption and vibration stress reduction.

In one configuration, if the thermally conductive material comprises aresin that cures as dielectric material, the thermally conductivematerial offers better abrasion resistance and greater adhesion tosurrounding components and interior of the housing than conductivegrease, for example.

In an alternate embodiment, the substrate 34, as an un-populated (bareboard) circuit board (e.g., ceramic substrate), has a coefficient ofthermal expansion (CTE) interface layer to match a first CTE of themetallic islands (e.g., heavy copper pours pattern) to a second CTE ofthe substrate 34 for thermal management. For example, the CTE interfacelayer comprises a dielectric layer (e.g., substantially planer layer) ofpolymer, plastic or fiber filled polymer that resides between themetallic islands (e.g., 30, 24 and 28) and the substrate 34. In oneillustrative example, the CTE interface layer comprises a polyimide orbismaleimide triazine (BT) material bonded to a substrate 34, such as aceramic substrate (e.g., FR4). Further, the CTE interface layer, whichcomprises a polyimide or bismaleimide triazine (BT) material bonded to asubstrate 34, may be used to provide a CTE compliance between asubstrate 34 and an ancillary substrate 46 or between substrate 34 and agate driver circuit board underlying the connector 32.

In one embodiment, the electronic assembly 200 of FIG. 9 is similar tothe electronic assembly 200 of FIG. 7, except that the electronicassembly 200 of FIG. 9 further includes a thermally conductive via 900(e.g., a plastic via, polymer via, a dielectric thermally conductivevia, a thermoplastic via or thermoplastic insert) in thermalcommunication with a heat sink metallic island 901 or ground plane on anopposite side of the substrate 34 from the metallic islands (24, 28,30). One or more thermally conductive vias 900 (e.g., thermoplastic viasor thermoplastic inserts) can be composed of a dielectric material thatis thermally conducting, but electrically insulated: (1) to ensure thatmetallic islands (28, 24, 30) do not form or facilitate an electricalconnection (e.g., an electrical short circuit, if the metallic island isconfigured to be electrically floating or at operational voltagepotential other than ground potential) or (2) to isolate different phaseoutputs of an inverter or electronic assembly 200 where a common groundplane is used between one or more metallic islands (24, 38, 30) and acorresponding heat sink metallic island 901 or ground plane.

In an alternate embodiment, the electronic assembly 200 of FIG. 9 issimilar to the electronic assembly 200 of FIG. 7, except that theelectronic assembly 200 of FIG. 9 further includes a thermallyconductive via 900, a blind conductive via, or plated through-hole inthermal communication with a heat sink metallic island 901 or groundplane on an opposite side of the substrate 34 from the metallic islands(24, 28, 30), where the thermally conductive via 900 comprises anelectrically conductive and thermally conductive metallic via . Forexample, in certain embodiments of this disclosure, thermally conductivevias 900 can connect (e.g., electrically and mechanically) one or moreof the metallic islands (28, 24, 30) on a first side of the substrate 34with one or more heat-sink metallic islands 901 or one or more groundplanes on a second side of the substrate 34, where the second side isopposite the first side. FIG. 9 shows generally that thermallyconductive vias 900 (e.g., dielectric thermally conductive vias,thermally conductive metallic vias, or both) 900 are connected (e.g.,thermally, mechanically, or electrically, or any combination of theforegoing connection types) between the primary metallic island 24 andthe metallic ground plane 901, between the tertiary metallic island 28and the heat-sink metallic island 901 (also referred to as a metallicground plane or a phase-specific ground plane), and between thequaternary metallic island 30 and the metallic ground plane 901. Likereference numbers in FIG. 7 and FIG. 8 indicate like elements orfeatures.

FIG. 10 is a perspective view of an illustrative example of a fluidcooling system 900 that incorporates the electronic assembly 200 ofFIG. 1. The fluid cooling system 900 comprises a radiator 950 that iscoupled to a pump 952 with tubing 958. In turn, the pump 952 is coupledto an electronic assembly 200 via tubing (956, 962, 943). The radiator950 has connection ports (948, 951). At least one connection port (e.g.,951) is connected to a pump inlet 954 or pump outlet 956 via tubing 958,where the opposite connection 964 from the pump 952 is connected to theelectronic assembly 200 via tubing. For example, a first radiatorconnection port 951 is coupled to a pump inlet 954, whereas a secondradiator connection port 948 is coupled to a pump outlet 964 throughtubing (944, 946), one or more fittings 947, internal channels withinthe electronic assembly 200, and tubing (943, 962, 956).

The electronic assembly 200 has a first enclosure portion 100 and asecond enclosure portion 102 that are secured together to form ahousing. The housing also features a third enclosure portion 104 and thefourth enclosure portion 106. The first enclosure portion 100 has afirst inlet 116 and first outlet 118. The second enclosure portion 102has a second inlet 120 and the second outlet 122.

As illustrated, the pump outlet 964 is coupled to the first inlet 116and the second inlet 120 of the electronic assembly 200 via tubes (956,962, 943) and tee fittings, Y-fittings or other appropriate connectors947. Similarly, the second radiator port is coupled to the first outlet118 and the second outlet 122 via tubes and tee fittings, Y-fittings, orother appropriate connectors 947.

During or prior to operation, the radiator 950 is filled with a fluid orcoolant. The radiator 950 can provide a reservoir of coolant; thechannels and associated chambers within the electronic assembly 200 canprovide a reservoir of coolant, or both the radiator 950 the electronicassembly 200 can provide a reservoir of coolant. The pump 952 conveysfluid or coolant into the first inlet 116 for circulation of the fluidor coolant within the first enclosure portion 100. The fluid or coolantexits the first enclosure portion 100 at the first outlet 118 that iscoupled to the radiator 950 with tubing. Similarly, the pump 952 conveysfluid or coolant into a second inlet 120 for circulation of the fluid orcoolant within the second enclosure portion 102. The fluid or coolantexits the second enclosure portion 102 at the second outlet 122 that iscoupled to the radiator 952 with tubing.

The circuit board assembly 11 may be manufactured in accordance withvarious techniques, where some examples follow here. The circuit boardassembly 11 (e.g., power switching printed circuit board) is populatedwith or by mounting surface mount film capacitor elements, connectorsockets and planar power switching devices on one side or both sides thesubstrate 34 and ancillary substrate 46. For example, the components maybe mounted using a pick-and-place mechanization. The electronic assemblyprovides control and gate driver functionality circuits including lowvoltage connector for battery and electric machine harness.

The housing (100, 102, 104, 106) may comprise a case or cover that ismolded (e.g., injection molded), constructed by three-dimensionalprinting or otherwise formed. For example, in one embodiment theelectronics assembly 200 can be made in a highly automated process usingthree-dimensional printing for the first enclosure portion 100 and thesecond enclosure portion 102 to support the formation on integralcoolant channels in the housing. The housing comprises a first enclosure100 and a second enclosure portion 102. Each enclosure portion (100,102) has an interior surface shape/profile and features that conform tothe shape and profile of parts and interconnects placed on the circuitboard assembly 11 and a control gate and driver circuit board underlyingconnector 32. Accordingly, the electronic assembly 200 is well suitedfor high density packaging and using less volume for the capacity (e.g.,current or power) output of the electronic assembly 200. In oneconfiguration, the substrate 34 may be connected to the ancillarysubstrate 46 (or gate driver circuit board) by using a ball grid array(BGA) interconnect. For instance, an assembled substrate 34 withcomponents mounted thereon could go through reflow process with controland gate drive circuit board.

The connecters (36, 38, 40, 42, 44) comprise surface mount connectorsthat support plug (pin) and socket type of electrical connectionsbetween the load (e.g., electric motor, generator or machine) and theenergy source (e.g., DC energy source) for the electronic assembly 200.The connectors are populated between capacitor elements and planarchipsets of the first semiconductor switch 20 and the secondsemiconductor switch 22. The above placement of the connectors (36, 38,40, 42, 44) in the electronic assembly 200 supports electrical designfunctionality (e.g., minimization of system inductance and avoidance ofunnecessary current loops), thermal design functionality (e.g., spacebetween chipsets (20,22) and capacitors (56) used to separate parts thatoperate at substantial temperature difference and also socket increaseoverall surface area for improved heat sinking), and mechanicalfunctionality (e.g., minimization of overall area needed for circuitboard 11).

In one embodiment, the ancillary substrate 46 or a circuit boardunderlying connector 32 comprises a gate driver circuit and controlboard. The ancillary substrate 46 may be associated with a gate drivercircuit for controlling one or more phases of the first semiconductorswitches 20 and the second semiconductor switches. The gate drivercircuit may be miniaturized using method of Application SpecificIntegrated Circuit (ASIC). ASIC used to miniaturize gate driver circuitnot only simplifies the layout of the conductive by circuit confinementbut also increases immunity from electromagnetic interference and strayeffects caused by change in current over time and change in voltage overtime. The gate driver circuit features a current sensing circuit and lowvoltage control with discrete circuits. In one configuration, thecurrent sensing circuit is placed close to or adjacent to inverteralternating current output or one or more metallic islands, where thecurrent sensing circuit is accompanied by any necessary shielding andflux/field concentrators. The low voltage control and discrete circuitscan be embedded within a Field Programmable Gate Array (FPGA) anddiscrete electronics parts and integrated circuits. The gate drivercircuit and control board is populated with surface mount low voltageconnector harness connection with battery and sensors placed on electricmotor/generator driven by inverter.

In one embodiment, the housing can be formed by a three-dimensional(3-D) printed process or injection molded process. The housing hassurface shape/profile and features conforming to the circuit boardassembly 11 used in inverter assembly. The housing facilitates enhancedthermal management of the semiconductor switches (20, 22), filmcapacitor 56 (e.g., film capacitors), connectors (e.g., 36, 38, 40, 42,44) interconnects on the circuit board 11, and all heat generatingcircuits placed on the circuit board 11.

To form the housing with 3-D printing process, first a laser scanner isused to scan the circuit board 11. The laser scanner produces one ormore three-dimensional images of the profile of the circuit board.Separate laser images of each side of the circuit board 11 are collectedas input data. Second, a pre-form thermal interface material (TIM)screen that can be deposited on the component-populated circuit board11. TIM allows a close contact between heat generating components orregions, heat conducting components or regions, or heat radiatingcomponents or regions within assembly 200 and an interior of thehousing. In an alternate configuration, a layer of TIM with an optimizedthickness (e.g., optimized for electrical insulation and thermalconduction) can be deployed on the interior face of first enclosureportion 100 and the second enclosure portion 102.

Third, the housing can be composed of a polymer, plastic or metallicmaterial. In one configuration, the housing is 3-D printed from a lightweight metal such as aluminum or a polymer metallic composite based onone or more scanned profiles or scanned images collected by the laserscanner. The 3-D printed housing conforms to parts and features ofcircuit board 11. For example, the 3-D printed housing of inverter cantouch or contact all components and parts on the circuit board 11. Asillustrated in FIG. 4 and FIG. 7, the 3-D printed housing will havebuilt-in coolant channels or micro-channels for coolant that createsturbulent flow of coolant. The coolant channels making double-sidedcooling of the semiconductor switches (20, 22) effective along with thelateral withdrawal of heat from power devices by thermal management ofinterconnects. This automated 3-D printing process for the inverterhousing will effectively reduce unused volume or empty space withinelectronic assembly 200 that supports reduced package size of theelectronic assembly 200. The 3-D printing will allow thicknessoptimization of the inverter housing/enclosure, therefore, 3-D printingprocess if exploited properly can significantly reduce the materialneeded, and thus a significant costs saving can be realized as the 3-Dprinting process matures. The 3-D printed housing facilitates improvedaccess of the semiconductor switches (20, 22) to thermal conductiveliquid that results in a higher power rating for the inverter.

In an alternate embodiment, injection molding could be used to form thehousing or enclosure portions (100, 102). The housing promotesresistance to vibrations and shocks because the enclosure portions (100,102) are tightly packed with TIM and the circuit board 11, encapsulatedwith TIM. Unused and exposed areas of circuit board 11 will haveconductive land patterns or metallic islands to effectively increasesoverall contact area between circuit board 11 and the pre-formed thermalinterface material (TIM). TIM provides electrical insulation and thermalconduction between the circuit board assembly 11 parts and the housing,such as the first enclosure portion 100 and the second enclosure portion102.

A TIM layer can be placed, wrapped, injected, sprayed or deposited overone or more of the following parts or components within the inverterassembly: the enclosures (100 102), the substrate 34, the ancillarysubstrate 46, printed circuit board 11, capacitors 56, metallic islands(30, 24, 28), strips, pads, islands or fin shaped metallic features orpatterns on the surface of the circuit board 11, connectors or powersockets (36, 38, 40, 42, 44), any heat generating circuits on controland gate driver circuit board, any parts that need containment forvulnerability to vibration and shocks, and/or any parts that wouldotherwise be susceptible to thermal shocks or temperature swings. Thethermal interface material (TIM) between inverter circuit board 11 andenclosure portions (100, 102) helps to realize high-capacity (e.g.,current output), high packaging density (e.g., current output perspatial volume occupied by the assembly 200).

TIM facilitates enhanced heat dissipation from the electronic assembly200, such as a possible, double-sided cooling approach for thesemiconductor switches (20, 22). For example, TIM might enable asignificant increase in the number of power and thermal cycles for thesemiconductor switches (20, 22). This heat dissipation approachpotentially results in an improvement in semiconductor devicereliability as compared to power semiconductor devices used inconventional electronic assemblies. Thermal interface material (TIM)that is bonded to the interior and components of the assembly 200 tendsto minimize thermal resistance from junction to coolant channels in theheat exchanger (inverter cold plate). An increased margin betweenallowed maximum junction temperature (e.g., Tj_max, such asapproximately 175 degrees Celsius and beyond) for power devices andmaximum coolant temperature (e.g., as high as 105 degrees Celsius)provide an opportunity for decreased die size of the semiconductordevices.

Having described the preferred embodiment, it will become apparent thatvarious modifications can be made without departing from the scope ofthe invention as defined in the accompanying claims.

The following is claimed:
 1. An electronic assembly for an inverter, theelectronic assembly comprising: a substrate having a dielectric layerand metallic circuit traces; a plurality of terminals for connection toa direct current source; a first semiconductor and a secondsemiconductor coupled together between the terminals of the directcurrent source; and a primary metallic island located in a primary zonebetween the first semiconductor and the second semiconductor, theprimary metallic island having a greater height or thickness than themetallic circuit traces, the primary metallic island providing a heatsink to radiate heat.
 2. The electronic assembly according to claim 1wherein the heat is conducted away from the primary metallic islandthrough thermally conductive dielectric vias connected between theprimary metallic island and a ground plane or heat sink on an oppositeside of the substrate.
 3. The electronic assembly according to claim 1further comprising: a first enclosure portion overlying the substrateand the primary metallic island; wherein the heat is conducted away fromthe primary metallic island through a first enclosure portion in contactwith, above or in close proximity to the primary metallic island.
 4. Theelectronic assembly according to claim 3 wherein a thermal interfacematerial, a thermally conductive adhesive or thermally conductivelubricant is used between the primary metallic island and the firstenclosure portion.
 5. The electronic assembly according to claim 3wherein the first semiconductor and the second semiconductor comprisesurface mount transistors that are mounted on the substrate andelectrically connected to corresponding ones of the metallic circuittraces and wherein the first enclosure portion has an inner surface witha mating shape and size that corresponds to the contour or adjoiningsurface of the primary metallic island and the surface mounttransistors.
 6. The electronic assembly according to claim 3 wherein thefirst enclosure portion comprises a group of channels or micro-channelswithin an adjoining cover or enclosure in contact with, above or inclose proximity to the primary metallic island for transfer of the heatfrom the primary metallic island.
 7. The electronic assembly accordingto claim 1 further comprising: a plurality of first surface mountconnectors mounted on the substrate that are electrically connected tothe terminals; and a secondary metallic island located in a secondaryzone between adjacent surface mount connectors.
 8. The electronicassembly according to claim 7 wherein the first enclosure portioncomprises a group of channels or micro-channels within the firstenclosure portion, and where an inner surface of the first enclosureportion is in contact with, above or in close proximity to the secondarymetallic island for transfer of the heat from the secondary metallicisland.
 9. The electronic assembly according to claim 1 furthercomprising: a plurality of second surface mount connectors mounted onthe substrate that are electrically connected to a first phase outputterminal of the first semiconductor and the second semiconductor; and atertiary metallic island located in a tertiary zone between adjacentsurface mount connectors.
 10. The electronic assembly according to claim9 wherein the first enclosure portion comprises a group ofmicro-channels within the first enclosure portion, and where an innersurface of the first enclosure portion is in contact with, above or inclose proximity to the tertiary metallic island for transfer of the heatfrom the tertiary metallic island.
 11. An electronic assembly for aninverter, the electronic assembly comprising: a substrate having adielectric layer and metallic circuit traces; a first enclosure portionfor mounting above the substrate, the first enclosure portion having aplurality of coolant channels located therein; a second enclosureportion for mounting below the substrate; a plurality of terminals forconnection to a direct current source; a first semiconductor and asecond semiconductor coupled together between the terminals of thedirect current source; and a primary metallic island located in aprimary zone between the first semiconductor and the secondsemiconductor, the primary metallic island having a greater height orthickness than the metallic circuit traces, the primary metallic islandproviding a heat sink to radiate heat for transfer via the coolantchannels within an adjoining first enclosure portion in contact with,above or in close proximity to the primary metallic island.
 12. Theelectronic assembly according to claim 11 wherein the coolant channelsof the first enclosure portion further comprises: a series of inletcoolant channels for conveying/circulating the coolant within the firstenclosure portion, the inlet channels adapted to receive coolant from aninlet port.
 13. The electronic assembly according to claim 11 whereinthe coolant channels of the first enclosure portion further comprises: aseries of outlet coolant channels for conveying/circulating the coolantwithin the first enclosure portion, the outlet channels adapted toreceive coolant from an outlet port.
 14. The electronic assemblyaccording to claim 11 wherein the coolant channels of first enclosureportion comprise: an inlet port in the first enclosure portion forreceiving a coolant; a series of inlet coolant channels forconveying/circulating the coolant within the first enclosure portion,the channels in communication with a distributor portion associated withthe port; a series of outlet coolant channels for conveying/circulatingthe coolant within the first enclosure portion, the channels incommunication with an transition portion between the curved arrangementand the outlet coolant channels; and an outlet port in the firstenclosure portion for exhausting the coolant.
 15. The method accordingto claim 14 further comprising: a radiator for receiving the exhaustedcoolant; a pump associated with the radiator to circulate the coolantwithin the radiator and first enclosure portion.
 16. The electronicassembly according to claim 11 further comprising: a plurality of firstsurface mount connectors mounted on the substrate that are electricallyconnected to the terminals or to ones of the conductive traces; and asecondary metallic island located in a secondary zone between adjacentsurface mount connectors.
 17. The electronic assembly according to claim16 further comprising: a series of inlet coolant channels or a series ofoutlet coolant channels in the first enclosure portion and underlyingthe secondary metallic island.
 18. The electronic assembly according toclaim 11 further comprising: a plurality of second surface mountconnectors mounted on the substrate that are electrically connected to afirst phase output terminal of the first semiconductor and the secondsemiconductor; and a tertiary metallic island located in a tertiary zonebetween adjacent surface mount connectors.
 19. The electronic assemblyaccording to claim 18 further comprising: a series of inlet coolantchannels or a series of outlet coolant channels in the first enclosureportion and underlying the tertiary metallic island.
 20. The electronicassembly according to claim 11 wherein an inner surface of the firstenclosure portion conforms in size and shape to mate with the substrateas populated with one or more surface-mount components.
 21. Theelectronic assembly according to claim 20 wherein the surface mountcomponents comprise one or more of the following components:transistors, capacitors and connectors.
 22. The electronic assemblyaccording to claim 11 wherein the first semiconductor and the secondsemiconductor comprise surface mount transistors that are mounted on thesubstrate and electrically connected to corresponding ones of themetallic circuit traces.
 23. The electronic assembly according to claim11 wherein the second enclosure portion has one or more cooling fins forheat dissipation.
 24. The electronic assembly according to claim 11wherein the first enclosure portion and the second enclosure portionmate to form a housing for the substrate.